805 



fact that in the islands of llie archipelago outside the region of the 

 Moluccas such rocks as the "old basic igneous rocks" are of frequent 

 occurrence, for instance in Celebes, Borneo, and Suinalra. For lïiany 

 of them in Sumatra only a pre-oecene age has been established ; in 

 Borneo several must be grouped as cretaceous, as has also been 

 observed already by Vkrbkf.k. 



In the eastern peninsula of Celebes near the Moluccas Hotz ^) 

 describes peridotites and volcanic breccias conformable between the 

 lower neogene strata, and not far from it sheets of amphibole diorite 

 have been observed by Wannkr *) between the jnarls of the same 

 age. In the environs of the Tukalii mountains peridotites and volcanic 

 breccias occui- conformably in the partly tertiary, perhaps partly 

 mesozoic "Buru-formation", while, conversely, limestone with chert 

 occurs also in the basic eruptive rocks. 



Furthermore it may be added : 



a. that in Timor in the permian and triassic sediments basic 

 intrusive- and effusive-rocks and their tuflfs are of frequent occurrence,*)*) 



b. that in the valley of the Nimassi (Central Timor) intrusive 

 sheets of diabase occur with distinct contact phenomena in upper- 

 triassic limestone, as demonstrated by me during Prof. Molengraaff's 

 Timor Expedition. 



c. that along the const of Dutch Timor basic and more acid 

 eruptive rocks occur frequently together with serpentine and serp- 

 entine conglomerate, which may belong to the tertiary (or young 

 mesozoic) period as deemed plausible by me elsewhere. ^) 



d. that in the North-Western part of the island of Great-Obi 

 andesite which is quite similar to the young andesites of the archi- 

 pelago is overlain conformably by serpentine. *) 



e. that in the island of Letti are found partly intensely meta- 

 morphosed basic effusive rocks of permian and probably also of 

 later origin. ') 



') W. Hotz. Vorlaufige Mitteilung fiber geologische Beobachtungen in Ost-Gelebes. 

 Zeitschr. der Deutsch. Geol. Ges. 1913. Monatsber. n». 6. p. 329. 



') J. Wanner. Beitrage zur Geologie des Ost-Arms der Insel Gelebes. Neues 

 Jahrb f. Min, etc, Beil. Bd. XXIX, 1910, p. 765. 



3) J. Wanner Geol. von West-Timor. Geol. Rundsch. IV. 1913. p. 145. 



*) G. A. F. MoLKNGRAAFF. I'^oldcd mountain chains, overthiust sheets and block 

 faulted mountains in the East Indian Archipelago. Compte Rendu du Xllme Congr. 

 Geol. intern. Toionto. 1913. p. 689 seqq. 



») H. A. Brouwer, I. c p. 38. 



^) Ibid. p. 45. 



7) G. A. F. MoLENGRAAFF and H. A. Brouv^er. De geologie van bet eiland 

 Letti, 1, c. p. 22 seqq. 



